Xueke Sun

Three-Dimensional Inverse Opal Photonic Crystal Substrates toward Efficient Capture of Circulating Tumor Cells

Artificial fractal structures have attracted considerable scientific interest in circulating tumor cells (CTCs) detection and capture, which plays a pivotal role in the diagnosis and prognosis of cancer. Herein, we designed a bionic TiO2 inverse opal photonic crystal (IOPC) structure for highly efficient immunocapture of CTCs by combination of a magnetic Fe3O4@C6@silane nanoparticles with anti-EpCAM (antiepithelial cell adhesion molecule) and microchannel structure. Porous structure and dimension of IOPC TiO2 can be precisely controlled for mimicking cellular components, and anti-EpCAM antibody was further modified on IOPC interface by conjugating with polydopamine (PDA). The improvement of CTCs capture efficiency reaches a surprising factor of 20 for the IOPC interface compared to that on flat glass, suggesting that the IOPCs are responsible for the dramatic enhancement of the capture efficiency of MCF-7 cells. IOPC substrate with pore size of 415 nm leads to the optimal CTCs capture efficiency of 92% with 1 mL/h. Besides the cell affinity, IOPCs also have the advantage of light scattering property which can enhance the excitation and emission light of fluorescence labels, facilitating the real-time monitoring of CTCs capture. The IOPC-based platform demonstrates excellent performance in CTCs capture, which will take an important step toward specific recognition of disease-related rare cells.

Photoluminescence enhancement of carbon dots induced by hybrids of photonic crystals and gold–silver alloy nanoparticles

Carbon dots are attracting worldwide interest owing to their unique optical properties and great potential for application. However, orange/red emission carbon dots are still rare and exhibit relatively low efficiency. In this work, we present a novel strategy to enhance the fluorescence intensity of orange carbon dots, by synergistically manipulating an electromagnetic field through opal photonic crystals and the localized surface plasmon resonance of a metal structure. An optimum intensity enhancement of 25-fold was obtained for a modulated sample of PMMA opal photonic crystals and 53-fold for PMMA opal photonic crystals/Au–Ag alloy plasmon hybrids. The local electromagnetic field distribution for the PMMA opal photonic crystals/Au–Ag hybrid is calculated by the finite difference time domain method. Furthermore, a fingerprint identification system based on synergistic modulation is realized in the composite system, which provides novel insights into the potential applications of carbon dot films.

Luminescence carbon dot-based nanofibers for a water-insoluble drug release system and their monitoring of drug release

Drug release systems with fluorescence detection have emerged as a potential application for the biological area of diagnosis and therapy. Carbon dots (CDs) are a promising fluorescence probe for application in a drug release system due to their excellent biocompatibility, low toxicity, chemical inertness, and non-blinking fluorescence emission. Herein, we developed a composite nanocarrier based on fluorescent CDs and polyvinylpyrrolidone (PVP) through an electrospinning technology. The as-prepared PVP/CD-ketoprofen (PVP/CD-KET) composite nanofiber presents bright blue-light fluorescence with a photoluminescence quantum yield (QY) of 65.7% and was utilized for loading a water-insoluble drug and moreover for monitoring the drug release process. In vitro tests indicate that the photoluminescence emission intensity of the CDs and the cumulative amount of KET released from the PVP/CD-KET composite nanofiber gradually increase with the release time. Furthermore, the emission intensity of the CDs as a function of the cumulative released amount of KET can be summarized by a power function. The correlation between the emission intensity of CDs and drug release amount can be potentially used to monitor the drug release process.

Amphiphilic silane modified multifunctional nanoparticles for ratiometric oxygen sensing

Precise detection of dissolved oxygen (DO) at the cellular level plays a pivotal role in the diagnosis of many diseases and intraoperative observation. In this work, we designed a ratiometric fluorescence DO sensing probe based on efficient energy transfer at long wavelength excitation. The oxygen probe Pt(II)-meso-tetra(pentafluorophenyl)porphine (PtTFPP), the reference dye Coumarin 6 (C6) and Fe3O4 NPs were encapsulated by amphiphilic silane at room temperature. The results indicate the important role of C6 molecules in the composite, serving as not only the ratiometric reference probe, but also the sensitizer of efficient energy transfer. The emission from PtTFPP can be greatly enhanced by 20 times based on the energy transfer pathway from C6 relative to that with the intrinsic excitation wavelength. DO sensing was successfully carried out based on ratiometric fluorescence in the imitation environment and at the cellular level under a confocal microscope. In addition, the cell magnetic separation function makes the composite possess great potential in DO sensing related medical applications.